Combination of tt̅ cross section measurements and constraints on the mass of the top quark and its decays into charged Higgs bosons

Abstract

We combine measurements of the top quark pair production cross section in pp̅ collisions in the l+jets, ll, and Tl final states (where l is an electron or muon) at a center of mass energy of √s=1.96 TeV in 1 fb⁻¹ of data collected with the D0 detector. For a top quark mass of 170 GeV/c², we obtain σ_tt̅=8.18_-0.87^+0.98 pb in agreement with the theoretical prediction. Based on predictions from higher order quantum chromodynamics, we extract a mass for the top quark from the combined tt̅ cross section, consistent with the world average of the top quark mass. In addition, the ratios of tt̅ cross sections in different final states are used to set upper limits on the branching fractions B(t→H⁺b→t⁺∨b) and B(t→H⁺b→cs̅b) as a function of the charged Higgs boson mass.